Output window with venting means for use with a vacuum electron device

Abstract

An output window for a vacuum electron device comprises an output waveguide, an intermediate layer of dielectric material joined to the interior of the output waveguide with a vacuum-tight seal, and upper and lower layers of dielectric material spaced apart from the intermediate layer and arranged above and below, respectively, the intermediate layer in a vertical orientation of the output waveguide. The upper and lower layers including openings. Supports extend inwardly into the output waveguide and support the upper and lower layers. Pillars extend through the openings in the lower layer and support the intermediate layer. The openings in the upper and lower layers permit a venting of a region between the upper layer and the intermediate layer and a region between the lower layer and the intermediate layer during the sealing of the intermediate layer while the intermediate layer is supported by the pillars.

1. An output window for a vacuum electron device, comprising:
 an output waveguide; 
 an intermediate layer of dielectric material joined to the interior of the output waveguide with a vacuum-tight seal; 
 upper and lower layers of dielectric material spaced apart from the intermediate layer and arranged above and below, respectively, the intermediate layer in a vertical orientation of the output waveguide, the upper and lower layers including respective openings; 
 supports extending inwardly into the output waveguide and supporting the upper and lower layers, respectively; 
 pillars extending through the openings in the lower layer and supporting the intermediate layer; 
 wherein the openings in the upper and lower layers permit a venting of a region between the upper layer and the intermediate layer and a region between the lower layer and the intermediate layer during the sealing of the intermediate layer while the intermediate layer is supported by the pillars. 
 
     
     
       2. An output window as claimed in  claim 1 , wherein the upper and lower layers are respectively joined to the interior of the output waveguide. 
     
     
       3. An output window as claimed in  claim 1 , wherein each layer is sealed to the interior of the output waveguide by brazing. 
     
     
       4. An output window as claimed in  claim 1 , wherein the intermediate layer has a thickness of approximately one quarter of the wavelength of a center frequency of a band transmitted by the window. 
     
     
       5. An output window as claimed in  claim 4 , wherein the spacing between each of the upper and lower layers and the intermediate layer is respectively approximately one eighth of the wavelength of the center frequency of the band transmitted by the window. 
     
     
       6. An output window as claimed in  claim 4 , wherein the upper and lower layers each have a thickness of approximately one twentieth of the center frequency of the band transmitted by the window. 
     
     
       7. An output window as claimed in  claim 1 , wherein each of the layers of dielectric material comprises ceramic material. 
     
     
       8. An electron device having an output window as claimed in  claim 1 . 
     
     
       9. An electron device as claimed in  claim 8 , in which the device is a gyrotron travelling wave tube. 
     
     
       10. A method of making an output window for a vacuum electron device, comprising the steps of:
 supporting upper and lower layers of dielectric material on supports extending into an output waveguide; 
 supporting an intermediate layer of dielectric material between the upper and lower layers in spaced relationship therewith on pillars extending through openings in the lower layer; and 
 sealing the intermediate layer to the output waveguide to provide a vacuum-tight seal between the intermediate layer and the interior of the output waveguide. 
 
     
     
       11. A method as claimed in  claim 10 , including providing the openings in the upper and lower layers to enable regions between the intermediate layer and the upper and lower layers, respectively, to be vented during the sealing step. 
     
     
       12. A method as claimed in  claim 10 , including joining the upper and lower layers to the interior of the output waveguide. 
     
     
       13. A method as claimed in  claim 10 , including the steps of brazing each layer to the interior of the output waveguide. 
     
     
       14. A method as claimed in  claim 10 , including providing the thickness of the intermediate layer to be approximately one quarter of the wavelength of a center frequency of a band transmitted by the window. 
     
     
       15. A method as claimed in  claim 14 , including providing the spacing between each of the upper and lower layers and the intermediate layer to be respectively approximately one eighth of the wavelength of the center frequency of the band transmitted by the window. 
     
     
       16. A method as claimed in  claim 14 , including providing the thickness of each of the upper and lower layers to be respectively approximately one twentieth of the center frequency of the band transmitted by the window. 
     
     
       17. A method as claimed in  claim 10 , including making each of the layers of dielectric material of ceramic material. 
     
     
       18. A method of making an electron device, comprising the steps of making an output window as claimed in  claim 10 . 
     
     
       19. A method as claimed in  claim 18 , wherein the electron device is a gyrotron travelling wave tube.